Isoprenoid diphoshates are key metabolic intermediates for the biosynthesis of many classes of molecules required by single and multicellular organisms. They fulfill a wide variety of cellular functions: components of cell membranes (sterols), electron transport (ubiquinones), signal transduction (prenylated proteins), and cell wall biosynthesis (dolichols)-essential for viability. A detailed understanding of the mechanisms by which isoprenoids elicit their effects has been limited by the difficulty of getting isoprenoid diphosphates into live cells. Echelon Biosciences, Inc. will develop a simple new method for delivering isoprenoid diphosphates and/or their precursors into cells passively and without disruption of cellular integrity. Two methods will be used, either independently or in tandem to accomplish this task. In the first approach, we will test the feasibility of delivering isoprenoid monophosphate and derivatives into cells, which then can be converted by an intracellular kinase to the diphosphates. The second approach will employ shuttle molecules that will be developed based on prior expertise at Echelon for the intracellular delivery of phosphoinositides.